[Amps] grid resonance

[Tom W8JI]

>> Is there a way to measure impedance and Q with it Vic?
>
> No, although the sharpness of the dip gives a clue to the 
> Q.

The sharpness of the dip only gives an indication of the 
load impedance seen at the grid or gate. Distance, turns 
ratio between the oscillator coil and the DUT, and many 
other things determine dip depth and shape.

All the dip meter measures is loading on the gate or grid. 
Nothing else.

Where we get in trouble is thinking things tell us more than 
they really do.

By the way, a short mobile antenna is indeed the equivalent 
of a series resonant circuit. The parallel resonance of the 
coil is a long way away in a good system.

Parallel resonance only approaches series resonance when the 
L to C ratio is very large.  That can actually mean a sharp 
response without higher Q than something with a wide 
response. If we want to measure something, we should measure 
what we actually want to know whenever possible. Otherwise 
we can build a house of cards.

73 Tom